This invention relates generally to the control of a fluid motor. More particularly, it relates to apparatus for controlling a fluid motor such that it steps in discrete increments while maintaining a significant holding torque.
A step motor basically is an electromagnetic DC motor rotatable in discrete steps or increments which may be controlled precisely. One need only keep track of the number and direction of steps taken in order to know the position of the rotor at all times. There are many applications where precise control is needed, and thus where the use of a step motor would be desirable.
For reasons of economy, the typical step motor has a low torque capability. Thus, in applications where precise control would be desirable but where high torque capacity is required, the step motor generally is not used.
A conventional fluid motor may have a high torque capability, and often is used in applications having heavy load characteristics. However, the conventional fluid motor generally is free-running, and is not capable of stepping in discrete increments. There is a need in the art for some type of control apparatus which will enable a conventional fluid motor to step in discrete increments.